For thousands of years, the level of CO2 in the atmosphere fluctuated relatively consistently (air bubbles trapped in Antarctic ice provide a record of the past). But, since around the 19th century, CO2 levels have been rising and haven’t really stopped. We know this partly because of the work of Charles Keeling. Keeling developed the first technique for accurately measuring CO2 in the air. He set-up a continuous measurement of CO2 on a volcano in Hawaii in 1958.

When you plot out the data collected over years of CO2 observations, you can see a steady upward curve. It became known as the “Keeling Curve” and was an easy-to-understand piece of evidence for global warming. Ralph Keeling, Charles’ son, has now taken over his father’s work and serves as the Principal Investigator for the Atmospheric Oxygen Research Group at the Scripps Institution of Oceanography in San Diego. He spoke to us on the 60th anniversary of his father’s CO2 measurements.